CN106162846A - A kind of two users NOMA descending efficiency optimization method considering SIC energy consumption - Google Patents

Abstract

The invention discloses a kind of two users' NOMA downlink efficiency optimization method considering SIC energy consumption, first obtain the transmitting power P of base station, the channel condition H between user 1 and base station₁, channel condition H between user 2 and base station₂, and receiver user is the signal voltage difference thresholding θ performing to carry out required for SIC multiplexed signals separation；By channel condition, preferable user performs SIC, is optimized power partition coefficient according to the channel conditions of the preferable user of channel condition, obtains the power allocation scheme of optimum；The present invention is applicable to consider two users' NOMA downlink system of SIC energy consumption, compared with two users' NOMA system not considering SIC energy consumption, while ensureing overall system capacity, preferably improves the total energy effect of system.

Description

A kind of two users NOMA descending efficiency optimization method considering SIC energy consumption

Technical field

The invention belongs to wireless communication technology field, more particularly, under a kind of two users NOMA considering SIC energy consumption Line link efficiency optimization method.

Background technology

Growth and the scarcity of frequency spectrum resource, NOMA (Non-orthogonal Multiple in the face of traffic demand Access, non-orthogonal multiple accesses) technology is as a kind of power domain multiplex technique, with it in power system capacity and the availability of frequency spectrum Advantage and become one of hot-candidate of next generation mobile communication multiple access technology.The frequency spectrum resource being different from 4G system is by one User individually occupies, and same frequency spectrum resource is distributed to multiple user by NOMA system, and by distributing different power coefficients Realize power domain multiplexing.The preferable user of channel condition is by performing SIC (Successive Interference Cancellation, successive interference cancellation) eliminate the interference from other users, thus increase total appearance of system greatly Amount.

Energy-saving and emission-reduction, the green communications reducing power consumption need to carry out NOMA system energy as the requirement of next generation mobile communication The work that effect optimizes.Traditional NOMA system power factor allocation scheme all turns to target with overall system capacity maximum, also Lack the consideration for SIC signal processing energy expenditure, therefore according to traditional NOMA system power factor allocation scheme System total energy effect can be made relatively low.

Summary of the invention

For disadvantages described above or the Improvement requirement of prior art, the invention provides a kind of two users considering SIC energy consumption NOMA downlink efficiency optimization method, its object is to promote the energy of NOMA system in the case of safeguards system total throughout Effect.

For achieving the above object, according to one aspect of the present invention, it is provided that a kind of two users NOMA considering SIC energy consumption Downlink efficiency optimization method, comprises the steps:

(1) BS (Base Station, base station) updates the essential information of current network, and obtains according to current network information Base station transmitting power P, community perform two channel conditions between user and base station of NOMA communication, and receiver user For performing to carry out required for SIC the signal difference threshold value θ of multiplexed signals separation；

(2) according to the channel condition H of the preferable user of channel condition in two users₂, base station transmitting power P and described Signal difference threshold value θ determines two user power partition coefficient a that efficiency is optimum₁And a₂；

a₁Refer to the power partition coefficient of the user that channel condition is poor, a in two users₂It it is channel bar in two users The power partition coefficient of the preferable user of part；

(3) according to above-mentioned two user power partition coefficient, two users are carried out power distribution, poor for channel condition User 1 distribute a₁P, distributes a for the preferable user of channel condition 2₂P, is derived from maximum efficiency.

Preferably, two users' NOMA downlink efficiency optimization method of above-mentioned consideration SIC energy consumption, its step (2) includes Following sub-step:

(2.1) comparing the channel condition of two users, good user is user 2 to determine channel condition, and its channel condition is H₂；

(2.2) according to described channel condition H₂, base station transmitting power P and signal difference threshold value θ determine that efficiency is optimum Two user power partition coefficient a₁And a₂；

$a_1=\frac{1}{2}+\frac{1}{2}{\[{\left(\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{4}\right)}^2+\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{2}\]}^{\frac{1}{2}}-\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{8};$

$a_2=\frac{1}{2}-\frac{1}{2}{\[{\left(\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{4}\right)}^2+\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{2}\]}^{\frac{1}{2}}+\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{8};$

Wherein, n refers to user's thermal noise；a₁+a₂=1.

Preferably, two users' NOMA downlink efficiency optimization method of above-mentioned consideration SIC energy consumption, its step (2.2) is wrapped Include following sub-step:

(2.2.1) two users are transmitted the signal being overlapped mutually by base station simultaneously,

The signal that user 1 receives

The signal that user 2 receives

Wherein, n₁For the thermal noise of user 1, n₂For user 2 thermal noise；n₁, n₂～CN (0,1), n₁=n₂=n；Wherein, s₁ For sending base station to the information of user 1, s₂The information of user 2 it is sent to for base station；

(2.2.2) performed SIC by user 2, first decode the information of user 1, by the information of user 1 from the signal being overlapped mutually In remove the information of rear further decoding user 2 self；

Thus, user 1 need not perform SIC, thus reduces the user 1 energy consumption on SIC signal processing；

(2.2.3) outage probability of user 2 is obtained

In NOMA, perform SIC for receiver smoothly, a need to be met₁＞ a₂, user 2 has certain outage probability；I.e. two Individual user power partition coefficient difference is the biggest, and user 2 more easily performs SIC；Two user power partition coefficient differences are the least, and user 2 It is more difficult to perform SIC, and has certain probability to produce interruption；

(2.2.4) data rate of two users is obtained:

$R_1={\log }_2(\frac{a_1{{\mathrm{PH}}_1}^2}{a_2{{\mathrm{PH}}_1}^2+n_1}+1),$

$R_2={\log }_2(\frac{a_2{{\mathrm{PH}}_2}^2}{n_2}+1)\·\exp (-\frac{\mathrm{\θ}}{(a_1-a_2)P});$

Wherein, R₁Refer to the data rate of user 1, R₂Refer to the data rate of user 2；

(2.2.5) according to the definition of efficiency, under the SIC circuit energy consumption considering user 2, the energy of NOMA system is obtained Efficacious prescriptions journey

Wherein P_SICRefer to that user 2 receiver performs the energy that SIC is consumed；

(2.2.6) according to a₁+a₂=1, efficiency equation transform is become the power partition coefficient a about user 2₂Function,

${\mathrm{\η}}_{EE}=\frac{{\log }_2(\frac{(1-a_2){{\mathrm{PH}}_1}^2}{a_2{{\mathrm{PH}}_1}^2+n_1}+1)+{\log }_2(\frac{a_2{{\mathrm{PH}}_2}^2}{n_2}+1)\·\exp (-\frac{\mathrm{\θ}}{(1-2a_2)P})}{P+P_{SIC}};$

(2.2.7) by making η_EEMaximum, carries out derivation acquisition to above-mentioned function

$a_2=\frac{1}{2}-\frac{1}{2}{\[{\left(\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{4}\right)}^2+\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{2}\]}^{\frac{1}{2}}+\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{8};$

And further according to a₁+a₂=1 obtains

$a_1=\frac{1}{2}+\frac{1}{2}{\[{\left(\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{4}\right)}^2+\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{2}\]}^{\frac{1}{2}}-\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{8};$

So far, the power partition coefficient of two users obtains the most, BS according to above power partition coefficient to two users Carry out power distribution, be user 1 and distribute a₁P, distributes a for user 2₂P can obtain maximum efficiency.

In general, by the contemplated above technical scheme of the present invention compared with prior art, it is possible to show under acquirement Benefit effect:

(1) two users NOMA descending efficiency optimization method of the consideration SIC energy consumption that the present invention provides, is the merit of two users Rate distribution proposes optimisation strategy；User carries out multiplexing under same time slot or frequency domain to power domain, and a telex network changes Becoming two telex networks, owing to the channel condition of a user is very poor, another user will not be too much to its interference produced Affecting its performance, therefore handling capacity and the total speed of user of whole system is promoted, significantly by efficiency equation Derivation is got back the optimum power partition coefficient of efficiency, the most both ensure that the total capacity of system, and had made again efficiency optimum, maximum limit Degree ground reduces energy expenditure；

(2) two users NOMA descending efficiency optimization method of the consideration SIC energy consumption that the present invention provides, it is contemplated that reality The energy that middle execution SIC Process circuitry is consumed, compared with two users' NOMA downlink system not considering SIC energy consumption, energy Enough energy that more accurately descriptive system is consumed；

In the NOMA downlink system not considering SIC energy consumption, it is believed that the power consumed only has the transmitting merit of base station Rate, and think that system energy efficiency is about user 2 power partition coefficient a₂Monotonic increasing function, i.e. at a₂=0.5, a₁When=0.5 it is System efficiency obtains maximum；But, when the power partition coefficient of two users is equal, SIC circuit will be unable to distinguish two Signal, causes the receiver of user 2 received signal cannot be performed SIC, thus reduces the total transmission capacity of system, Cause the decline of system total energy efficiency eventually；

In general, it is proposed that above technical scheme compared with the method not considering SIC energy consumption in prior art, On the basis of ensureing power system capacity, improve system total energy effect, the performance of whole network can be promoted, both met future mobile communications Requirement to spectrum efficiency, meets again the trend of green communications.

Accompanying drawing explanation

Fig. 1 is two users NOMA downlink system model schematic in embodiment；

The flow process of two users NOMA descending efficiency optimization method of the consideration SIC energy consumption that Fig. 2 provides for the embodiment of the present invention Figure；

The efficiency optimization method that Fig. 3 provides for embodiment and two users NOMA descending efficiency optimization not considering SIC energy consumption The system of method can imitate true comparison diagram.

Detailed description of the invention

In order to make the purpose of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, right The present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, and It is not used in the restriction present invention.If additionally, technical characteristic involved in each embodiment of invention described below The conflict of not constituting each other just can be mutually combined.

Two users NOMA descending efficiency prioritization scheme of the consideration SIC energy consumption that the present invention provides is good according to channel condition The information of user and the power of launching of base station determine the power partition coefficient of two users, the effect optimum to reach efficiency.

Shown in Fig. 1, it it is two users NOMA downlink network system model schematic diagram in embodiment；Wherein, channel condition The user of difference is user 1, and the user that channel condition is good is user 2, and user 2 first passes through the information performing SIC decoding user 1, and Eliminated, the information of further decoding user 2, to reach to improve the effect of system spectral efficiency；In embodiment, user obeys independence Poisson distribution, according to the characteristic of Poisson distribution, the geometric properties of any community is all consistent with one of them community, can be by wherein The analysis conclusion of one community expands to all communities in cellular network.

Shown in Fig. 2, it is the flow chart of two users NOMA descending efficiency optimization method of the consideration SIC energy consumption of embodiment confession, Specifically include following steps:

(1) system initialization, obtains the transmitting power P of base station, two users and base in community according to current network information Channel condition between standing, and receiver user is the signal difference thresholding threshold performing to carry out required for SIC multiplexed signals separation Value θ；In embodiment, receiver user is the signal difference threshold value θ=3mV performing to carry out required for SIC multiplexed signals separation；

(2) channel condition of two users is compared, the channel condition H of the user 1 of bad channel conditions₁Represent, channel bar The channel condition H of the user 2 that part is good₂Represent；Performed SIC by user 2, first decode the information of user 1, solve again after removing it The information of code self, user 1 then need not perform SIC；

Channel condition H according to user 2₂, base station transmitting power P and receiver user carry out required for performing SIC The signal difference thresholding θ that multiplexed signals separates determines the power partition coefficient a of two users of efficiency optimum₁And a₂,

$a_1=\frac{1}{2}+\frac{1}{2}{\[{\left(\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{4}\right)}^2+\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{2}\]}^{\frac{1}{2}}-\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{8},$

$a_2=\frac{1}{2}-\frac{1}{2}{\[{\left(\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{4}\right)}^2+\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{2}\]}^{\frac{1}{2}}+\frac{\frac{2\mathrm{\θ}}{P}\·\left(\ln \right(\frac{{\mathrm{PH}}_2}{n})-1)}{8};$

(3) according to above-mentioned two user power partition coefficient, base station is that user 1 distributes a₁The power of P, distributes for user 2 a₂P；Now, the total energy effect η of system_EEObtain maximum；On the basis of ensureing spectrum efficiency, reach the useful effect that efficiency is optimum Really.

Shown in Fig. 3, be embodiment provide considerations SIC energy consumption two users' NOMA downlink system total energy effect optimization method and Do not consider that two users' downlink system total energy effect optimization method of SIC energy consumption compares, both efficiency simulation comparison figures；Wherein, Parameter is: receiver user is the signal difference threshold value θ=3mV, noise n performing to carry out required for SIC multiplexed signals separation =1 × 10^-14W, user 2 performs the circuit institute consumed energy P of SIC_SIC=0.2W, the channel condition H between user 1 and base station₁ =-116.12dB, the channel condition H between user 2 and base station₂=-107.95dB, does not consider that two users of SIC energy consumption are descending A in system total energy effect optimization method₂=0.499.

From figure 3, it can be seen that in contrast to not consider two users' downlink system total energy effect optimization method of SIC energy consumption, implement Two users' downlink system total energy effect optimization method of the consideration SIC energy consumption that example provides can improve the performance efficiency of whole network.

As it will be easily appreciated by one skilled in the art that and the foregoing is only presently preferred embodiments of the present invention, not in order to Limit the present invention, all any amendment, equivalent and improvement etc. made within the spirit and principles in the present invention, all should comprise Within protection scope of the present invention.

Claims (3)

1. two users' NOMA downlink efficiency optimization method considering SIC energy consumption, it is characterised in that include walking as follows Rapid:

(1) obtain according to current network information base station transmitting power P, community perform NOMA communication two users and base station it Between channel condition, and receiver user is the signal difference threshold value θ performing to carry out required for SIC multiplexed signals separation；

(2) according to the channel condition H of the preferable user of channel condition in two users₂, described base station transmitting power P and described Signal difference threshold value θ determines two user power partition coefficient a that efficiency is optimum₁And a₂；

Wherein, a₁Refer to the power partition coefficient of the user that channel condition is poor, a in two users₂It it is channel bar in two users The power partition coefficient of the preferable user of part；

(3) according to said two user power partition coefficient, two users are carried out power distribution, for the use that channel condition is poor Family distribution a₁P, for channel condition, preferable user distributes a₂P, it is thus achieved that maximum efficiency.

2. two users' NOMA downlink efficiency optimization method as claimed in claim 1, it is characterised in that described step (2) Including following sub-step:

(2.1) compare the channel condition of two users, obtain the current channel condition H of the good user 2 of channel condition₂；

(2.2) according to described channel condition H₂, base station transmitting power P and signal difference threshold value θ determine that efficiency is optimum two User power partition coefficient a₁And a₂；

$a_1=\frac{1}{2}+\frac{1}{2}{\[{\left(\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{4}\right)}^2+\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{2}\]}^{\frac{1}{2}}-\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{8};$

$a_2=\frac{1}{2}-\frac{1}{2}{\[{\left(\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{4}\right)}^2+\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{2}\]}^{\frac{1}{2}}+\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{8};$

Wherein, n refers to user's thermal noise；a₁+a₂=1.

3. two users' NOMA downlink efficiency optimization method as claimed in claim 2, it is characterised in that described step (2.2) following sub-step is included:

(2.2.1) transmitted the signal being overlapped mutually to two users by base station simultaneously,

The signal that user 1 receives

The signal that user 2 receives

Wherein, n₁For the thermal noise of user 1, n₂For user 2 thermal noise；n₁,n₂～CN (0,1), n₁=n₂=n；Wherein, s₁For base Station is sent to the information of user 1, s₂The information of user 2 it is sent to for base station；

(2.2.2) performed SIC by user 2, first decode the information of user 1, the information of user 1 is moved from the signal being overlapped mutually Information except rear further decoding user 2 self；

(2.2.3) outage probability of user 2 is obtained

(2.2.4) data rate of two users is obtained:

$R_1={\log }_2(\frac{a_1{{\mathrm{PH}}_1}^2}{a_2{{\mathrm{PH}}_1}^2+n_1}+1),$

$R_2={\log }_2(\frac{a_2{{\mathrm{PH}}_2}^2}{n_2}+1)\·\exp (-\frac{\mathrm{\θ}}{(a_1-a_2)P});$

Wherein, R₁Refer to the data rate of user 1, R₂Refer to the data rate of user 2；

(2.2.5) under the SIC circuit energy consumption considering user 2, the efficiency equation of NOMA system is obtained

Wherein P_SICRefer to that user 2 performs the energy that SIC is consumed；

(2.2.6) according to a₁+a₂=1, efficiency equation transform is become the power partition coefficient a about user 2₂Function,

${\mathrm{\η}}_{EE}=\frac{{\log }_2(\frac{(1-a_2){{\mathrm{PH}}_1}^2}{a_2{{\mathrm{PH}}_1}^2+n_1}+1)+{\log }_2(\frac{a_2{{\mathrm{PH}}_2}^2}{n_2}+1)\·\exp (-\frac{\mathrm{\θ}}{(1-2a_2)P})}{P+P_{SIC}};$

(2.2.7) η is made_EEMaximum, carries out derivation acquisition to described function

$a_2=\frac{1}{2}-\frac{1}{2}{\[{\left(\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{4}\right)}^2+\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{2}\]}^{\frac{1}{2}}+\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{8};$

And further according to a₁+a₂=1 obtains

$a_1=\frac{1}{2}+\frac{1}{2}{\[{\left(\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{4}\right)}^2+\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{2}\]}^{\frac{1}{2}}-\frac{\frac{2\mathrm{\θ}}{P}\·\left(ln\right(\frac{{\mathrm{PH}}_2}{n})-1)}{8}.$